Apparatus and method for cleaning, neutralizing and recirculating exhaust air in a confined environment

ABSTRACT

Thermal energy content of exhaust air containing particulate and gas contaminants is withdrawn from a confined environment by a circulation system which liquid scrubs some of the contaminants from the exhaust flow, removes the scrubbing liquid, and then catalyzes or neutralizes gas contaminants into benign gases before discharging the flow back into the confined environment.

CROSS-REFERENCE TO RELATED INVENTION

[0001] This invention and application is a continuation-in-part of theinvention described in U.S. patent application Ser. No. 09/399,125,filed Sep. 20, 1999, for an “Apparatus and Method for Liquid ScrubbingContaminants from a Gas and Flow,” now U.S. Pat. No. 6,241,809, issuedJun. 5, 2001. The disclosure of this prior application is incorporatedherein by this reference.

INTRODUCTION

[0002] This invention relates to a new and improved method and apparatuswhich eliminates offensive and toxic particulate and gaseouscontaminants, such as smoke, grease, volatile organic compounds, carbonmonoxide and other toxic gases, from an exhaust flow, and recirculatingthe cleaned and benign exhaust flow back into a confined environmentfrom which the exhaust originated. In addition to avoiding the dischargeof undesirable and potentially harmful contaminants into the ambientenvironment, recirculating the cleaned and benign exhaust flow saves asubstantial portion of the thermal energy of the air from the exhaustflow that would otherwise be lost by discharging the exhaust flow intothe ambient environment. Thus, the present invention substantiallyreduces the cost of heating, cooling or otherwise conditioning makeupair to replace the conditioned air which is normally lost in an exhaustflow discharged into the ambient environment.

BACKGROUND OF THE INVENTION

[0003] Modern environmental concerns and regulations impose significantrequirements for removing contaminants and undesirable constituents fromthe exhaust flow discharged into the ambient environment from industrialand other commercial operations. In some cases, the discharged exhaustflow must be cleaned or otherwise conditioned before it may it isdischarged. For example, food preparation establishments are nowrequired, or will soon be required, to remove the relatively highconcentrations of smoke and fat airborne contaminants from the cookingexhaust. Not only is smoke generated while cooking the food, butparticulate matter such as grease and fat and volatile contaminants suchas odor are also created. Moreover, the hydrocarbon fuels which areburned while cooking the food generate carbon monoxide, which is toxicand may be lethal in concentrated doses. Other examples of business andindustrial operations which generate exhaust with offensive and toxicparticulate and gaseous contaminants are automobile repair shops,clothes drycleaning operations, and waste and water treatment plants.

[0004] Industrial and business operations frequently discharge theexhaust flow from the confined interior environment of the establishmentinto the ambient environment outside of the establishment. Usually theexhaust consists not only of the smoke, odor, particulates, volatileorganic compounds, carbon monoxide and other toxic gases, but also airdrawn from within the confined environment of the establishment which isused to carry these contaminants outside of the establishment and intothe ambient environment. Some types of these industrial and businessoperations, such as restaurants or food preparation establishments,generate a relatively large amount of such contaminants, and the amountof air consumed from within the confined environment to exhaust thecontaminants is substantial. Makeup air must be admitted into theconfined environment of the establishment to replace the air consumed bythe exhaust flow.

[0005] The amount of makeup air required to replace the air of theexhaust flow is usually a significant portion of the overall airrequired to condition the interior confined environment of theestablishment. Because the interior air used in the exhaust flow isdrawn from the heated, cooled or otherwise conditioned air or within theinterior confined environment, the makeup air admitted into the confinedenvironment to replace the exhaust air flow must also be heated, cooledor otherwise conditioned. Otherwise, the desired thermal environmentwithin the establishment could not be maintained. Of course, the thermalenergy content of the air within the exhaust flow is when the exhaustflow is discharged into the ambient environment.

[0006] The energy required to heat, cool or otherwise condition makeupair may be a significant operating cost of the establishment. Forexample, the size and energy consumption of the heating and coolingequipment required to condition the makeup air for a small fast foodrestaurant is approximately four times the size and capacity that wouldbe otherwise required if air was not withdrawn from within the interiorof the confined environment as part of the cooking exhaust flow into theambient environment. Considerable expense is involved in obtaining theincreased capacity of the heating and cooling equipment for conditioningthe makeup air, and in operating that equipment.

[0007] One of the significant drawbacks to recirculating the exhaust airfrom confined environments such as food preparation establishments, hasbeen an inability to clean the contaminants from the exhaust air in acost-efficient manner. The previous invention referenced above offers arelatively low cost and highly effective solution of ridding the exhaustair of particulate and gaseous contaminants, thus offering thepossibility of recirculating the cleaned and benign exhaust flow backinto the confined environment.

[0008] It is with respect to these and other considerations that thepresent invention has evolved.

SUMMARY OF THE INVENTION

[0009] One primary improvement available from the present invention isan improved cability to remove offensive and harmful particulate andgaseous contaminants from an exhaust flow, and to convert toxic gaseouscomponents of the exhaust flow into neutralized or benign non-toxiccomponents, thereby allowing the cleaned and neutralized exhaust flow tobe recirculated back into a confined environment of a commercial orindustrial establishment. Another improvement relates to recirculating asignificant portion of the cleaned and benign exhaust flow to avoidlosing the energy content of the conditioned air which is part of theexhaust flow. Another improvement relates to reducing the capacity ofthe heating, cooling and air conditioning equipment and the cost ofoperating that equipment to condition makeup air to compensate for theair consumed by the exhaust flow. The operating costs of a foodpreparation establishment, or any other type of industrial or commercialestablishment may be substantially reduced.

[0010] These and other improvements are achieved in a recirculationsystem for retaining substantial thermal energy content of air drawnfrom within a confined environment in which offensive and toxicparticulate and gaseous constituents are generated as exhaustcontaminants. The recirculation system includes a collector devicelocated within the confined environment to receive and establish a flowof the exhaust contaminants and air from within the confinedenvironment, and a cleaner device connected to receive the flow of theexhaust contaminants and air from the exhaust collector device. Thecleaner comprises a scrubber module, a liquid removal module and afiltering and conversion module connected in series through which theexhaust flow passes. The scrubber module may include flow passagewaysthrough which the flow of exhaust contaminants and air passes and intowhich cleaning liquid is distributed for mixture with and entrainment ofthe particulate contaminants of the flow. The liquid removal moduleremoves the cleaning liquid from the flow from the scrubber module. Thefiltering and conversion module includes an odor-removing filter forremoving odor from the exhaust flow from the liquid removal module, andthe filtering and conversion module also includes a catalyst whichfacilitates conversion of toxic gases in the exhaust flow from theliquid removal module into benign gases, such as the conversion ofcarbon monoxide into carbon dioxide. A delivery device is located withinthe confined environment to receive the cleaned and neutralized flowfrom the cleaner device and to discharge the flow into the confinedenvironment.

[0011] Other useful aspects of the recirculation system include anexhaust collection hood located over the source of the exhaust and intowhich the cleaned and benign flow from the cleaner may be discharged. Itis also useful for the catalyst to operate at room temperature tooxidize the toxic gases into benign gases, by using air from the exhaustflow. A heater may periodically heat the catalyst to a predeterminedtemperature sufficient to regenerate the catalytic characteristics ofthe catalyst. A catalyst cell of the filtering and conversion module mayinclude a layer of particles of the catalyst and a layer of carbonparticles, and the heater may be positioned within the layer of catalystparticles. The filtering and conversion module may further comprise afilter device such as a HEPA, DOP or BAG filter, connected to receivethe flow from the liquid removal device. The scrubber module may includea baffle-defining structure comprising a plurality of vertically spacedand interdigitated deflection plates which define a serpentine-shapedflow passageway through which the flow of the exhaust contaminants andthe air move, and one or more liquid distributors positioned within eachpassageway to flow liquid cleaning agent into the exhaust flow. Theliquid removal device may comprise a curved sidewall structure alongwhich the flow moves in a curved motion to force liquid remaining in theflow from the scrubber module to coalesce into liquid and drain alongthe sidewall structure, and to cause contaminants in the flow to beforced against the sidewall structure and become entrained in theliquid.

[0012] The above noted and other improvements are also achieved by amethod of recirculating air to retain substantial thermal energy contentof the air drawn from within a confined environment of an establishmentwhich generates offensive and harmful particulate and gaseousconstituents as exhaust contaminants. The method includes establishing aflow of the exhaust contaminants and air from within the confinedenvironment, liquid scrubbing contaminants from the flow, moving theflow after liquid scrubbing in a curved path to force liquid mist tocoalesce into liquid by centrifugal force caused by moving the flow inthe curved path, removing the coalesced liquid from the flow, removingodor from the flow after the coalesced liquid has been removed,catalyzing toxic gases remaining in the flow into benign gases after thecoalesced liquid has been removed, and discharging the cleaned andneutralized flow into the confined environment.

[0013] Other useful aspects of the method include catalyzing toxic gasesinto benign gases at approximately room temperature, and periodicallyheating the catalyst to a predetermined temperature greater than roomtemperature to regenerate the catalytic characteristics of the catalyst.Still other useful aspects involve collecting the air and exhaustcontaminants from within the confined environment in an exhaustcollection hood and discharging the cleaned and neutralized exhaust flowinto the confined environment within the hood.

[0014] A more complete appreciation of the present invention and itsscope, and the manner in which it achieves the above noted improvements,can be obtained by reference to the following detailed description ofpresently preferred embodiments of the invention taken in connectionwith the accompanying drawings, which are briefly summarized below, andthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a partial perspective view of a confined environment ofa food preparation establishment, as one typical application of thepresent invention, in which a roof-mounted exhaust cleaner and exhaustrecirculation system incorporating the present invention are also shown.

[0016]FIG. 2 is an enlarged perspective view of the cleaner shown inFIG. 1 with portions broken away to reveal a scrubber module, a liquidremoval module and a filtering and conversion module of the cleaner.

[0017]FIG. 3 is an enlarged side elevation view of the cleaner shown inFIG. 2.

[0018]FIG. 4 is an enlarged side elevation view of a baffle-definingstructure of the scrubber module of the cleaner shown in FIGS. 2 and 3.

[0019]FIG. 5 is a further enlarged partial view of a portion of FIG. 4,illustrating flow turbulence and cleaning effects from thebaffle-defining structure of the scrubber module shown in FIG. 4.

[0020]FIG. 6 is a side elevation view of an alternative configuration ofthe baffle-defining structure of the scrubber module shown in FIG. 4.

[0021]FIG. 7 is an enlarged partial view of a portion of FIG. 6illustrating flow turbulence and cleaning effects from the scrubbermodule shown in FIG. 6.

[0022]FIG. 8 is a perspective and exploded view of a cyclone of theliquid removal module of the cleaner shown in FIGS. 2 and 3, withportions also broken out for clarity of illustration.

[0023]FIG. 9 is axially-sectioned side elevation view of a cyclone ofthe liquid removal module shown in FIG. 8.

[0024]FIG. 10 is a cross-sectional view of the cyclone shown in FIG. 9,taken substantially in the plane of line 10-10.

[0025]FIG. 11 is an enlarged elevational and vertical section view of agroup of catalytic cells of the filtering and conversion module of thecleaner shown in FIG. 3.

[0026]FIG. 12 is an enlarged atop view of one catalytic cell of thefiltering and conversion module shown in FIG. 11.

[0027]FIG. 13 is an enlarged vertical section view of the catalytic cellshown in FIG. 12, taken substantially in the plane of line 13-13.

DETAILED DESCRIPTION

[0028] A cleaner 20 embodying part of the present invention is shown inFIG. 1. The cleaner 20 is shown in a typical or exemplary use in arestaurant cooking-exhaust cleaning and recirculating application.However, the use of the invention is not limited to food preparationestablishments, but may be used in any confined environment in which avariety of different types of contaminants are created and from whichthose contaminants must be exhausted in a flow of air. Examples of otherbusiness and industrial establishments where the present invention isparticularly useful are automobile repair shops, clothes dry cleaningoperations, waste and water treatment plants. The contaminants may beany airborne particulate matter of solid or liquid substances or may bemolecules of hazardous gaseous substances. For example, in therestaurant cooking-exhaust cleaning application, the contaminants mayinclude grease and fat particles, smoke, volatile organic compounds,carbon monoxide and/or other particulates and gases creating undesirableodors, smoke and harmful constituents. The confined environment of thebusiness or industrial concern in which the present invention may beused, is intended to refer to a defined internal environment. A confinedenvironment includes the circumstance where there is some naturalentrance and loss of air within the confined environment, such as wouldoccur when doors to the confined environment are opened or closed, or asa result of normal internal air circulation. In this sense, the confinedenvironment does not necessarily mean an environment that is entirelyclosed, although an entirely closed environment would also be consideredas a confined environment.

[0029] The cleaner 20 is effective in removing substantially all of theparticulate contaminants and is effective in converting the hazardousgaseous substances into benign substances, so that a substantial portionof the exhaust flow may be recirculated into the confined environment.As a result of recirculating the cleaned and neutralized exhaust flowinto the confined environment, there is a reduced need for heating andcooling equipment to condition makeup air to replace the air consumed bythe exhaust flow, and the costs associated with operating thereduced-capacity heating and cooling equipment are also reduced.

[0030] In the exemplary cooking-exhaust cleaning and recirculating useshown in FIG. 1, the restaurant or other food preparation establishmenthas a food preparation area 21, including a counter-top cooker 22 suchas a stove top, a range, an oven, a wood-burning oven, an open broiler,a deep fryer or other cooking device which is fueled by a hydrocarbonfuel source, such as natural gas or propane. Heat from the counter-topcooker 22 is developed by burning the hydrocarbon fuel in an open flame.The exhaust from the combusted fuel contains carbon monoxide gas, whichis toxic and can be lethal in substantial doses. A collector device suchas a hood 23 is located above the counter-top cooker 22 to receive andcollect the cooking gas exhaust generated from the cooker 22. The cooker22 is the source of the exhaust contaminants. The exhaust received bythe hood 23 is removed from the food preparation area 21 as a result ofa blower 24 drawing an air from within the confined environment of thefood preparation area 21 through the hood 23. The withdrawn air liftsand otherwise transports the contaminants generated by the cooker 22 outof the confined environment.

[0031] The mixture of the withdrawn air and the contaminants forms anexhaust flow which is passed from the hood 23 and through a connectingexhaust duct 25 to the cleaner 20. The duct 25 channels the exhaust flowfrom the hood 23 through a ceiling 26 and a roof 27 and into the cleaner20, which may be mounted on the roof 27. Alternatively, the cleaner 20could be mounted in a space 28 between the ceiling 26 and the roof 27,if there is sufficient space, or on the floor of an adjacent room. Theblower 30 may be any other type of blower that can produce the necessarystatic pressure (suction) and flow rate for the cleaner 20.

[0032] The particulate and hazardous gaseous contaminants from thecooking exhaust are cleaned from the exhaust flow and neutralized whenthe exhaust flow passes through the cleaner 20. The cleaned andneutralized air is passed from the cleaner 20 into the blower 24, and isdischarged from the blower 24 into a recirculation duct 29. Asubstantial majority of the cleaned and neutralized air from the cleaner20 is discharged as return air from the recirculation duct 29 or otherdelivery device into the confined environment of the establishment orinto the food preparation area 22, to establish a loop re-circulationpath from the hood 23 through the cleaner 20 and back into the interiorof the confined environment of the food preparation establishment. Sincethe exhaust air is cleaned and neutralized by the cleaner 20, it ispractical and desirable to return the cleaned and neutralized air to theenvironment from which it was removed. Returning the cleaned andneutralized exhaust air has the advantage of preventing a substantialenergy loss, because the heat content of the cleaned and neutralizedexhaust air is returned to the confined environment from which theexhaust air originated, rather than being lost to the ambientenvironment surrounding the confined environment of the establishment.Recirculating or returning the cleaned and neutralized exhaust airavoids the necessity to completely condition makeup air for the amountof the exhaust air that would normally be discharged into the ambientenvironment.

[0033] The recirculation duct 29 includes a vent 30 through which asmall portion, for example about 20 percent, of the cleaned andneutralized exhaust air returning from the cleaner 20 is discharged intothe ambient environment outside of the confined environment. Discharginga small portion of the cleaned and neutralized exhaust air assures thata small portion of the entire air within the restaurant will be replacedcontinuously with a comparable amount of fresh air. The continuoussupply of a relatively small amount of fresh air is important inassuring an adequate oxygen content of the air within the confinedenvironment of the food preparation establishment, because an aspect ofthe present invention is the consumption of oxygen in the air whenneutralizing harmful gaseous contaminants, e.g. carbon monoxide, intoneutralized or benign gases, e.g. carbon dioxide. Thus, discharging asmall portion of the cleaned and neutralized return air through the vent30 assures that a small amount of makeup air will continually deliveradequate oxygen into the interior of the restaurant.

[0034] Although the cleaned and neutralized return air could be returneddirectly into the interior of the confined environment of therestaurant, the cleaned and neutralized exhaust air can also bedischarged into the hood 23. The hood 23 may be a conventionalcompensating hood 23, which is advantageously used for this purpose. Thereturn exhaust air is directed by a compensating hood in a flowpathwhich causes the return air to traverse generally in a direction acrossthe inlet to the hood 23. A significant portion of the delivered cleanedand neutralized exhaust air immediately reenters the exhaust flowleaving the hood 23 through the exhaust duct 25, thereby establishing acontinual re-circulation path from the hood, through the cleaner 20 andblower 24 and back into the hood 23. Nevertheless, some of the cleanedand neutralized return air delivered from the recirculation duct 29 intothe confined interior environment of the restaurant spills over into thefood preparation area 21. Consequently, the cleaned and neutralized airdischarged from the recirculation duct 29 must be capable of safe useand human consumption within the restaurant, even though a significantportion of that cleaned and neutralized air may again pass out of theconfined environment without contacting or being consumed by humans.

[0035] The basic components of the cleaner 20 are shown in FIGS. 2 and3. The cleaner 20 generally includes a scrubber module 40, a liquidremoval module 42 and a filtering and conversion module 44. The threemodules 40, 42 and 44 are contained within a scrubbing compartment 41, aliquid removal compartment 43 and a filtering and conversion compartment45, respectively, of a housing 46 for the cleaner 20. The housing 46includes side panels which define the exterior of the housing 46, andthe side panels are removable to allow access to the interior of thecleaner and its components. An interior partition 47 separates thescrubbing compartment 41 from the liquid removal compartment 43, andinterior diffuser plates 48, such as perforated steel plates, separatethe liquid removal compartment 43 from the filtering and conversioncompartment 45 within the housing 46. The cleaner housing 46 has aninternal frame structure 49 which supports and positions the modules 40,42 and 44, the housing side panels, the partition 47 and the diffuserplates 48, as well as the other components of the cleaner 20. A cleanercontrol and monitoring system (not specifically shown) is alsopreferably included within the cleaner, along with its sensors, tocontrol and monitor the functions of the cleaner 20 and the modules 40,42 and 44. Plumbing to conduct liquid and electrical conductors tosupply power to the modules 40, 42 and 44, as described below, are alsoincluded within the cleaner 20.

[0036] The scrubber module 40 includes a baffle-defining structure 50.The baffle structure 50 creates a plurality of serpentine flowpassageways 51 (FIGS. 4 and 6) through which water or other liquidcleaning agent cascades downwards while the exhaust air flows upwards.The resulting air/water mixing (or gas/liquid cleaning agent mixing) inthe passageways 51 causes the particulate contaminants in the exhaustair to collide with and become entrained within the water, therebyremoving the contaminants from the air passing upward out of the bafflestructure 50. The entrained particulate contaminants drain with thewater onto a sloped drain pan 52 at the bottom of the scrubber module40, below the baffle structure 50. The water and entrained contaminantsflow along the drain pan 52 and into a drain well 53. The configurationof the baffle structure 50 enhances the mixture of the flow and waterand the atomization of the water into droplets, thereby improving theremoval of particulate contaminants from the exhaust flow. The flow inthe passageways 51 continues to the upper portion of the scrubbingcompartment 41, above the baffle-defining structure 50, where the flowpasses through a diffuser 106 and is conducted to the liquid removalmodule 42.

[0037] The liquid removal module 42 receives the flow discharged fromthe scrubber module 40 and removes liquid mist and additionalcontaminants. The liquid removal module 42 comprises a cyclone 54. Theflow discharged from the scrubber module 40 into the cyclone 54commences whirling at a relatively high speed, centrifugally forcing thewater droplets and any remaining particulate contaminants to the outsideof the cyclone 54. The small water droplets coalesce into larger amountsof liquid water and entrain contaminant particles forced to the outsideof the cyclone 54. The water and entrained contaminants drain from thebottom of the cyclone 54 in a water exit conduit 55 which dischargesinto the drain well 53. The cleaned and dewatered air exits from the topof the cyclone 54 and is diffused by the diffuser plates 48 as it isrouted from the liquid removal compartment 43 to the filtering andconversion module 44.

[0038] The filtering and conversion module 44 includes one or moremesh-like moisture filters or mist eliminators 56 for removing a portionof any remaining moisture droplets, one or more pre-filters 61 forremoving any remaining large particulates, one or more high efficiencyfilters 57 (such as HEPA, DOP or BAG filters) for removing a portion ofany additional fine particulates, and one or more gas-removing andvolatile organic compounds-removing and converting catalytic cells 65.The filters 56, 57 and 61, and the catalytic cells 65 are connected tothe support frame structure 59 in the filtering compartment 45. Thefilters 56, 57 and 61, and the catalytic cells 65 remove essentially allof the remaining residual moisture and any remaining particulatecontaminates from the flow, and neutralize or convert gaseouscomponents, such as carbon monoxide, and volatile organic compounds,into benign substances before the exhaust flow is conducted into theblower 24 (FIG. 1) and through the recirculation duct 29 into therestaurant.

[0039] Because of the relatively high efficiency of the scrubber module40 and the liquid removal module 42, both in removing contaminants andmoisture, very little moisture or contaminants remain to be caught inthe filters 56, 57 and 61 of the filtering and conversion module 44,thereby substantially reducing the frequency for changing or servicingthe filters 56, 57 and 61. As is discussed below, the catalytic cells 65contain heaters for periodically re-generating the effectiveness of thematerials used within those catalytic cells, thereby also substantiallyreducing the frequency for changing or servicing the catalytic cells 65.

[0040] The scrubber module 40 of the cleaner 20 is described in moredetail with reference to FIGS. 2-7. The exhaust flow from the hood 23 issupplied through the exhaust duct 25 to the cleaner 20 through an inlet58 (FIG. 3) on a side panel of the housing 46, or through some otherconvenient access in the housing 46 into the scrubbing compartment 41below the baffle structure 50 and above the drain pan 52. The generallyvertically-oriented serpentine passageways 51 in the baffle structure 50permit the air to flow upwardly through the baffle structure into aspace in the scrubbing compartment 41 above the baffle structure 50.

[0041] Water or other cleaning liquid is distributed to the top andbottom of the baffle structure 50 through a pipe 60 which extends from arecirculating pump 62 (FIG. 3) having an inlet 63 which is connected tothe drain well 53. The pipe 60 is connected to an open manifolddistributor or closed tubing distributor 64 which extends above andbelow the passageways 51 in the baffle-defining structure 50. Althoughnot shown, additional distributors 64 may be positioned along the lengthof the passageways 51 within the baffle structure 50 to assure that anadequate supply of water or other cleaning fluid is available throughoutthe entire length of the passageways 51. Nozzles 66 (FIGS. 4 and 6),jets or openings spray or distribute the water downwards across the fulldimension of the passageways 51 (perpendicular to the view shown inFIGS. 4 and 6). The recirculating pump 62 pumps the water from the drainwell 53 and supplies it to the pipe 60 which is connected to themanifold pipes 64 located at the top of the baffle structure 50. Thewater which drains downward through the passageways 51 of the bafflestructure 50 falls onto the drain pan 52. The drain pan 52 slopes towardthe drain well 53 and the pump 62. The partition 47 divides space abovethe drain pan 52 in the scrubbing compartment 41 from the drain well 53in the liquid removal compartment 43, although a number of drain holes(not shown) are formed in the partition 47 at the level of the drain pan52 to allow water and contaminants to drain from the pan 52 into thewell 53. The drain holes in the partition 47 are below the water levelof the drain well 53 so as to confine the substantial majority of theentering flow in the scrubbing compartment 41 and cause the flow to passupwards through passageways 51 in the baffle structure 50.

[0042] The water drained into the well 53 is re-circulated from thedrain well 53 by the pump 62 to the scrubber module 40. Some portion ofthe solid contaminants may settle to the bottom in the drain well 53 andare not re-circulated with the water from the top of the drain well 53.When the amount of contaminants entrained in the water becomesexcessive, the cleaner will be flushed, either automatically by thecontrol system or under manual control, to rinse out the contaminantbuildup. Cleaning the cleaner is accomplished by opening a valve 67 on adrain pipe 68 (FIG. 3), and draining the water from the drain well 53.Simultaneously, or thereafter, a valve 69 on a water supply pipe 70 isopened, and the water in the drain well 53 is replaced with fresh water.The settled contaminants are flushed from the cleaner with the waterdrained from the drain well 53.

[0043] Alternatively, the scrubber module 40 need not re-circulate thewater. Instead, the water could be delivered directly from the supplypipe 70 to the pipe 60 and into the manifold distributors 64, and thewater collected from the drain well 53 would be drained through thedrain pipe 68. The drain pipe 68 preferably includes a trap (not shown)to cause the drain pipe 68 to siphon the water out of the drain well 53if the amount of water in the drain well 53 exceeds a predeterminedlevel. Furthermore, because of water evaporation into the flow in thescrubber module 40, additional water may need to be added from time totime, by opening the water supply valve 69. The addition of thereplenishing water may be accomplished either automatically by thecontrol system or manually.

[0044] To assist in rinsing the baffle structure 50, a hot waterdelivery pipe (not shown) may be connected to spray hot water directlyinto the baffle structure 50. One or more chemical liquid cleaningagents may also be connected to periodically deliver liquid cleaningagent to the water used in the scrubber module 40 or as the entirecleaning liquid used in the scrubber module 40. In the event thatcorrosive chemicals need to be removed from the exhaust flow, or thecleaning agent is corrosive, the interior surfaces of the flow path inthe cleaner should be coated or lined with an appropriate non-corrosiveor non-reactive lining material.

[0045] More details of one embodiment of 72 the baffle structure 50 aregenerally shown in FIGS. 4 and 5. The baffle structure embodiment 72 hasmultiple vertical sidewall plates 73 which are horizontally spaced apartfrom one another, which extend vertically from the top to the bottom ofthe baffle structure 72 and which extend horizontally (in a depth sense,perpendicular, as shown in FIG. 4) across the baffle structureembodiment 72. The sidewall plates 73 thereby divide the bafflestructure embodiment 72 into the flow passageways 51.

[0046] Attached to each sidewall plate 72 at vertically spaced locationsare deflection plates 74. The deflection plates 74 are positioned on thesidewall plates 73 so that one deflection plate 74 from one sidewallplate 73 projects into the space between two other deflection plates 74attached to the other sidewall plate 73. Arranged in this manner, thedeflection plates 74 overlap, causing an interdigitated arrangement ofthe deflection plates. This interdigitated arrangement establishes theserpentine shaped passageways 51 within the vertical space bounded byeach pair of horizontally adjacent sidewall plates 73. Lower supportbrackets 76 and mid support brackets 78 strengthen and maintain therigidity of the deflection plates 74, as well as help define thepassageways 51. The deflection plates 74 and the support brackets 76 and78 are connected to one another and to the sidewall plates 73 in aconventional manner, such as by welding in the case of metal or by anadhesive in the case of non-metallic material.

[0047] The major portion 80 of each deflection plate 74 is slopeddownward at a low or moderate slope, such as about a 15 to 45 degreeangle from the horizontal. An outer lip portion 82 of each deflectionplate 74 is considerably shorter than the major portion 80 and is slopeddownwards from the horizontal at a substantially greater angle, such asgreater than 45 degrees.

[0048] Configured in the manner described, the interdigitated deflectionplates 74 are substantially overlapped (about 51-80% overlapped). Therelatively high degree of overlap causes the passageways 51 to beconsiderably serpentine. As a result, a relatively high degree ofhorizontal flow reversal occurs in the serpentine passageways 51 andcauses improved interaction of the ascending air flow and descendingwater. The water and exhaust flow cannot avoid interaction and areforced into better mixing which results in improved contaminant removal,as is better understood by reference to FIG. 5.

[0049] Water which drains down from above accumulates on the topsurfaces of the major portions 80 of the deflection plates 74 and drainsoff of the lip portions 82 where the water falls into the air flowingupwards through the passageways 51. Because of the complete overlap ofthe interdigitated deflection plates 74, the air flow must pass througha waterfall-like curtain of water falling from each lip portion 82, asshown at 84. Thus, it is not possible for the flowing air to escapecontact with the water delivered from the lip portion 82 of eachdeflection plate 74, as would be the case if the deflection plates didnot overlap.

[0050] An enhanced air/water mixing zone represented at 86 exists undereach deflection plate 74, lower support bracket 76 and the mid supportbracket 78, and above the next lower deflection plate 74. The undersidesurfaces of the lip portion 82, the exposed major portion 80, the lowersupport bracket 76 and the mid support bracket 78 deflect air and waterthat are flowing upwards generally in the rotational path represented at86. The rotational path represented at 86 generally circumscribes anddefines the enhanced air/water mixing zone. The lip portion 82, inparticular, deflects the upward flowing air/water mixture back into theair/water mixing zone 86. The circulatory nature of the air flow in themixing zone 86 suspends a considerable amount of water in a vortex, thusincreasing the time that the water spends suspended in the air/watermixing zone 86 and maximizing the opportunity for contaminants tocollide with and become entrained in or chemically react with the water.

[0051] The narrowness of the passageway 51 between the lip portion 82and the sidewall plates 73 causes an acceleration of the flow in thisregion. Thus, as the water reaches the lip portion 82 of the deflectionplate, the accelerating air causes some of the water in thewaterfall-like curtain 84 to be buffeted upwards into the air/watermixing zone 86, rather than fall onto the next lower deflection plate.The relatively steep downward slope of the lip portion 82 of eachdeflection plate minimizes any surface tension adhesion of the water tothe bottom of the deflection plate to inhibit any adhering water frommoving up on the underside of the lip portion 82 against the force ofthe overall flow in the passageway 51 and against the force from thecirculatory vortex in the mixing zone 86. The rapid flow at the end ofthe lip portions 82 also breaks the water drops in the waterfall-likecurtain 84 into smaller droplets, thus increasing the surface area ofthe water droplets and finely dispersing the droplets to enhance theopportunity for collisions of the water droplets and the contaminants.The widening of the passageway 51 in the areas of the mixing zone 86beyond (in the flow direction) the lip portions 82 of the deflectionplates 74 assists in suspending the moisture in the mixing zone 86.

[0052] The configuration of the deflection plates 74 and the flowreversals in the serpentine passageway 51 increase the turbulence in theflow to enhance water droplet dispersion and to prevent the water fromcolliding with and draining down any of the surfaces in the passageways51. Many smaller turbulent areas are also created in the passageways 51,forcing the water to mix with the air to provide more opportunities forcontaminant removal.

[0053] The flow rate also contributes to the turbulence and air/watermixing efficiency in the passageway 51, since adjustment of the flowrate will cause more buffeting of the water into the air/water mixingzone 86 and more atomization of the water droplets. Also, the slopes ofthe major and lip portions 80 and 82, respectively, may be chosen toprevent the water, which lands on the top of the deflection plates 74,from draining too rapidly off the lip portion of the deflection plate74, so that the water cannot fall quickly through the exhaust flowwithout being buffeted back up into the air/water mixing zone 86.

[0054] An alternative embodiment 88 of the baffle-defining structure 50is shown in FIGS. 6 and 7. The baffle structure embodiment 88 is similarto that embodiment 72 shown in FIGS. 4 and 5, except for theconfiguration of the deflection plates 90 which are employed in theembodiment 88. The configuration of the deflection plates 90 and theresulting shape of the flow passageway 51 are particularly well suitedfor handling high volume exhaust through the baffle-defining structure50. The deflection plates 90, which project from the vertical sidewallplates 73 into each passageway 51, are vertically spaced from oneanother in each passageway 51, and interdigitate with one another ineach passageway 51, in a manner similar to that previously described. Alower support bracket 92 connects to the deflection plate 90 and extendsto the sidewall plate 73 to help define the passageway 51. Air flowsgenerally upwards through passageways 51 and water flows generallydownwards through passageways 51 while draining onto and being entrainedin the flow shaped by the deflection plates 90.

[0055] Each deflection plate 90 includes a medium sized and downwardangled upper portion 94, a largest sized and more steeply downwardlyangled middle portion 96, and a smallest sized and horizontallyextending outermost lip portion 98. Each support bracket 92 includes agenerally horizontally extending outer portion 100 which connects at itsouter end to the middle portion 96 slightly above the lip portion 98,and a relatively steeply inclined inner portion 102, which connects tothe sidewall plate 73 and to the outer portion 100. The inner portion102 extends at an inclination angle which is approximately parallel tothe angle of the middle portion 96 of the deflection plate 90. The outerportion 100 extends substantially horizontally at a converging angletoward the upper portion 94 of the deflection plate 90 which is locatedslightly below and horizontally displaced from the outer portion 100.The deflection plates 90 and the support brackets 92 are connected toone another and to the sidewall plates 73 in a conventional manner, suchas by welding in the case of metal or by an adhesive in the case ofnonmetallic material.

[0056] Because of the parallel relationship of the portions 96 and 102,a uniform cross section of the flow passageway 51 exists between theseportions, and the flow through the portion of the passageway betweenthese portions is more or less constant, except for turbulence inducedupstream of this location. However, the converging nature of theportions 94 and 100 continually reduce the cross sectional size of thepassageway, causing the flow rate therethrough to increase. The lipportion 98 projects into this portion of the flow passageway, whichfurther reduces the size, and increases the flow rate. The slope of themiddle portions 96 of the deflection plate 90 is high enough to causewater draining down onto the portion 96 to accelerate and shoot outalmost horizontally from the horizontal lip portion 98 as shown at 103(FIG. 7) into the increased-velocity flow adjacent to the lip portion 98in the passageway 51. Because the passageway is reduced in size betweenthe lip portion 98 and the sidewall plates 73, almost all of the waterat 103 is buffeted upwards into an air/water mixing zone 104 above thelip portion 98 in the constant cross-section region between the portions96 and 102.

[0057] Since the higher flow rate is sufficient to buffet almost all ofthe water at 103 into the air/water mixing zone 104, the bafflestructure embodiment 88 shown in FIGS. 6 and 7 is not as dependent on aneed to maintain the air and water in a major vortex 84 (FIGS. 4 and 5)to prevent the water from colliding with and draining down a sidesurface. Instead, any water that does collide with and drain down a sidesurface of the passageway 51 is quickly drained down to and directedentirely off of the lip portion 98 at 103, where the flow returns thewater to the air/water mixing zone 104, maximizing the time that thewater spends suspended in the air and maximizing the potential forcontaminants to be removed by the water particles. Because there is noneed for the vortex mixing zone 86 (FIGS. 4 and 5) the flow and volumehandling of the baffle-defining structure embodiment 88 shown in FIGS. 6and 7 is enhanced. In general, the baffle-defining structure embodiment88 shown in FIGS. 6 and 7 obtains all of the previously describedadvantages of the baffle-defining structure described in FIGS. 4 and 5,at a higher flow volume.

[0058] The embodiments 72 and 88 of the baffle structure 50 allow thewater and air to mix well enough to give the contaminants sufficientopportunity to collide with and become entrained within the water. Thewater sufficiently curtains the entire exhaust flow pathway, so thereare no substantial regions where the contaminated flow avoids contactwith the water altogether.

[0059] The embodiments 72 and 88 cause the water to flow directly intothe flow passageways 51 as the liquid flows off the lip portions 82 and98 of the deflection plates 74 and 90, as shown in FIGS. 5 and 7respectively. The flow buffets the water upward to cause air/liquidmixing zones whereby contaminants collide with liquid droplets andbecome entrained therein or chemically react therewith. The considerableoverlap of the deflection plates 74 and 90 causes flow reversals andensures that the liquid must interact with the flow, rather than draindown the side walls, as is a problem in previous liquid cleaners. Eachdeflection plate 74 and 90 slopes downward a sufficient degree to launchthe liquid droplets into the airstream, rather than to allow the liquiddroplets to adhere to the sidewalls. The deflection plates 74 and 90 aresupported by underside brackets 76, 78 and 92 which further assist indefining the vortex mixing zone 86 and the mixing zone 104, shown inFIGS. 5 and 7, respectively, for better mixing of the liquid and theflow. The flow rate, or velocity, is selected to maintain an enhancedamount of liquid in the air/liquid mixing zone, which again maximizesthe opportunity for contaminant entrainment in the liquid.

[0060] The exhaust flow and entrained water which pass upward from thebaffle-defining structure 50 contact an angled perforated plate 106, asshown in FIGS. 2 and 3. The perforated plate 106 serves as a gross waterseparating element in the flow exiting the scrubber module 40 before theair flows into the liquid removal module 42. The perforated plate 106permits the flow to pass therethrough, while evening out itsdistribution. The air flowing out of the top of the baffle structure 50has a considerable airborne water content, and the perforated plate 106removes some of the larger water droplets. The droplets carried in theair impact the perforated plate and coalesce or collect into largerdrops on the underside of the perforated plate 106. The collected waterdrains from the perforated plate 106 onto the partition 47 and fromthere drains back down through the baffle structure 50 to the drain pan52. After the air passes through the perforated plate 106, it passesthrough a rectangular hole 108 in the partition 47 which separates theflow outlet of the scrubber module 40 from the exhaust flow inlet of theliquid removal module 42.

[0061] More details of the liquid removal module 42 are shown in FIGS.2, 3, 8, 9 and 10. The cyclone 54 of the liquid removal module 42 isbasically of a conventional configuration and includes a generallycurved or cylindrically-shaped sidewall 110. A generally conical shapedbottom portion 112 is connected to the sidewall 110, and the relativelysmall water exit conduit 54 leads from the bottommost or pointed end ofthe conical bottom portion 112. A disc-shaped top end 116 is connectedto the sidewall 110. A relatively large air exit conduit 118 extendsthrough the top end 116. The air exit conduit 118 is axially positionedconcentrically with respect to the cylindrical sidewall 110 and extendsthe length of the cylindrical sidewall from the top end 116 down intothe conical bottom end portion 112. A lower end 120 (FIG. 9) of the airexit conduit 118 extends into the conical end portion 112 and issomewhat reduced in diameter and is spaced from the conical bottomportion. The air exit conduit 118 is held in position by its connectionto the top end 116 and by braces (not shown) between the lower end 120of the conduit 118 and the conical bottom end portion 112.

[0062] A generally rectangular inlet duct 122 is connected to therectangular hole 108 formed in the partition 47. The inlet duct 122extends from the hole 108 in the partition 47 into the sidewall 110 nearthe top of the cyclone 54. The cross-sectional size of the inlet ductdecreases slightly at the location where it joins the sidewall 110, asshown in FIGS. 8 and 10, thus causing the flow rate to increase as theair enters the cyclone 54. As shown in FIG. 10, the inlet duct 122 joinsthe cylindrical sidewall 110 tangentially, causing the accelerating flowentering the cyclone to initiate a circular swirling motion along theinside of the cylindrical sidewall 110 as shown by the flow arrow 123. Acyclonic whirling motion of the flow is created in the direction ofarrow 123 within the cylindrical sidewall 110 in an annular space 124defined by the inner surface of the sidewall 110 and the outer surfaceof the air exit conduit 118.

[0063] The downward spiraling flow in the annular space 124 experiencescentrifugal force as a result of following the curved path of thesidewall 110. A common flow velocity for air flowing through the blower30 (FIG. 1) may be about 1500 to 3600 linear feet per minute. Thecyclone 54 will greatly increase (e.g. double) this linear velocity. Thewhirling air enters the open lower end 120 of the air exit conduit 118after it has made multiple circuits around the sidewall 110 and flows upthrough the conduit 118 and exits from the cyclone at the open end ofthe conduit 118 at the top end 116.

[0064] The cyclonic whirling motion of the air in the annular space 124causes the water mist particles in the air exiting from the scrubbermodule 40 to be forced under centrifugal force onto the inner surface ofthe cylindrical sidewall 110. The centrifugal force causes the smallmist particles to coalesce into larger droplets. The droplets collect onand drain down the sidewall 110 into the conical bottom end portion 112and from there into the water exit conduit 55. Some of any particles ofcontaminants that remain in the air after the water scrubbing processare also forced to the inner surface of the cylindrical sidewall 110,where those particles become entrained in the water and collected in thedroplets which flow down and out of the cyclone 54. Thus, although theprimary purpose of the cyclone is to remove water from the air whichexits the scrubber module 40, the cyclone also achieves a level ofcontaminant removal as well. As shown in FIG. 3, the water exit conduit55 is connected to drain into the well collection area 53, allowing thecollected water to be reused in the scrubber module 40, in the mannerpreviously described.

[0065] The liquid removal capability of the cyclone 54 offers asignificant capability to remove moisture from the exhaust flow. Insteadof depending upon meshes, perforated plates and slam walls to attempt toremove moisture from the flow exiting the cleaner, the baffle structure50 and the cyclone 54 achieve an enhanced exhaust flow cleaningperformance. In circumstances requiring less substantial cleaning, thecyclone 54 may be replaced with they serpentine flow duct having aseries of 180 degree flow reversal elbows. The curved motion of the flowaround each 180 degree flow reversal elbow causes the mist to coalesceon the outside curved surface of the elbow in much the same manner thatthe missed coalesces on the curved surface of the cyclone 54.

[0066] A curved air deflection baffle 126 is positioned above the openupper end of the conduit 118 (FIGS. 3 and 8), and directs the airexiting the conduit 118 from the top of the cyclone 54 over and down tothe side of the cyclone 54 within the liquid removal compartment 43(FIG. 3). The curved air deflection baffle 126 maintains the kineticenergy of the flow exiting the cyclone 54, without dissipating that flowenergy by causing the flow to directly impact the sidewalls of thecleaner housing. The air deflection baffle 126 assists in directing theair throughout the compartment 43 where it diffuses through thediffusers 48. Various braces 128 (FIG. 8), the partition 47 and thecleaner frame structure 49 (FIGS. 2 and 3) support the cyclone 54 andits components and the air deflection baffle 126 within the cleanerhousing 46.

[0067] Details of the filtering and conversion module 44 are shown inFIGS. 2, 3 and 11-12. The decontaminated and dewatered flow exiting fromthe cyclone 54 is guided by the curved deflection baffle 126 from thetop of the cyclone into the flow diffusing portion of the liquid removalcompartment 43, and from there through diffusion plates 48 and misteliminators 56 of the filtering and conversion module 44 which aremounted on the support frame structure 59. Also connected to the support59 downstream of the diffusion plates 48 and mist eliminators 56 are oneor more pre-filters 61 and one or more conventional HEPA, DOP or BAGfilters 57. The flow continues from the diffusion plates 48 and misteliminators 56 through the filters 61 and 57 in the filteringcompartment 45 and then through the catalytic cells 65 before passingout of an opening in the cleaner housing 46 into the duct workconnecting the cleaner 20 to the blower 24 (FIG. 1).

[0068] Each mist eliminator 56 functions primarily as a fine de-misterto remove any residual amounts of water contained in the exhaust flowexiting the liquid removal module 42. The mist eliminators 56 arepreferably conventional, using a fine mesh screen which removes theairborne water mist prior to passing the air through the filters 57. Anyremaining mist in the air that collects on the diffusion plates 48 ormist eliminators 56 or on any of the housing sidewalls of the spaceinside of the liquid removal compartment 43 will drain down to a slopeddrain surface 130 (FIGS. 2 and 3) within the liquid removal compartment43 and from there into the drain well 53, where it may be re-circulatedfor use in the scrubber module 40. The pre-filters 61 are relatively lowefficiency (25-40%) filters that are about two inches thick and made ofporous fibers, such as fiberglass fibers, for removing any remaininglarge particles in order to protect the high efficiency filters 57 fromunnecessary contamination. The high efficiency filters 57 are effectivein removing very small contaminants and those which have resistedremoval in the scrubbing and liquid removal modules.

[0069] By the time the air has passed through the filters 57, thecleaner 20 will have typically removed about 98% of the contaminantsfrom the air, substantially better than the typical 40% efficiency offiltering devices used prior to the above-referenced invention. Of thetotal amount of the removed contaminants, the baffle structure 50 of thescrubber module 40 typically will have removed about 85%, the cyclone 54of the liquid removal module 42 typically will have removed about anadditional 10%, and the mist eliminators 56, pre-filters 61, highefficiency filters 57 typically will have removed approximately theremaining 3-5% of the particular contaminants. The baffle-definingstructure 50 will typically remove almost all of the particles having adiameter greater than or equal to five (5) microns in addition to somesmaller particles, while the liquid removal module 42 may remove almostall of the remaining particles greater than or equal to two (2) microns.

[0070] Certain types of molecular contaminants, such as odors, volatileorganic contaminants and gaseous compounds may remain in the exhaustflow. Carbon monoxide and other toxic gases are lethal to humans insubstantial amounts, and must therefore be removed or made benign beforethe exhaust air can be re-circulated into the confined environment.These chemical and gaseous substances will be substantially removed bythe catalytic cells 65. The most prevalent type of gaseous substancecontained in the exhaust flow exiting from the high efficiency filters57 will be toxic carbon monoxide gas generated by burning hydrocarbonfuels. The catalytic cells 65 are effective in converting the carbonmonoxide into benign carbon dioxide, while removing certain organicvolatile compounds, odors and other gaseous contaminants.

[0071] The details of an exemplary catalytic cell 65 are shown anddescribed in conjunction with FIGS. 11-13. Each catalytic cell 65 isformed by a plurality of individual cell panels 140 which are connectedat their ends in alternating Vees as shown in FIG. 11. Each cell panel140 includes a layer 142 of odor control particles 144, and a layer 146of room temperature catalyst particles 148, as shown in FIG. 13. Theodor control particles 144 of the layer 142 are preferably carbonparticles. The odor control particles are effective in eliminating odorsand organic volatile compounds as the flow passes through the layer 142of odor control particles 144 in the cell panel 140. The catalystparticles 148 of the layer 146 may be conventional mixed manganesecopper oxide (typically known as Hopcalite) or potassium permanganateparticles, which form a room-temperature catalyst to oxidize carbonmonoxide to carbon dioxide. The hazardous carbon monoxide gas in the airwhich passes through the layer 146 of catalyst particles 148 is oxidizedinto benign carbon dioxide, as the exhaust flow passes through the layer146 in the cell panel 140.

[0072] The layers 142 and 146 are held within a perimeter framestructure 150 of the cell panel 140, as shown in FIGS. 12 and 13. Acenter mesh-like divider 152 separates the layers 142 and 146. Outsidescreens 154 and 156 confine the odor control particles 144 and catalystparticles 148 within the cell panel 140. Spaces in the divider 152 andin the screens 154 and 156 permit the air flow through the cell panels140. The particles 144 and 148 are packed within the cell panel 140 inthe layers 142 and 146 with sufficient space around them to allow theair flow around and between those particles, so that the particles 144and 146 can have their intended affect on the exhaust flow. The materialfor the perimeter frame 150, the divider 152 and the screens 154 and 156is selected to be non-reactive to the odor control particles 144 and tothe catalyst particles 148. Typically, this material may be polyvinylchloride plastic material.

[0073] Occasionally the catalyst particles 148 must be renewed orreactivated to accomplish their catalyst function. This is performed byheating the catalyst particles 148 to a temperature of approximately 100degrees Celsius. With the catalyst particles 148 heated to thistemperature, any moisture absorbed in those particles is driven off andthe chemical constituents of the particles are reactivated to performtheir catalyst function. To heat the catalyst particles 148, anelectrical heating element 158 is embedded in the layer 146, as shown inFIG. 13. The electrical heating element 158 is a conventional electricalresistive heating element which delivers heat to the surroundingcatalyst particles 148 when electrical current is conducted by theheating element 158. The heat from the heating element 158 is alsobeneficial in driving off any moisture which may accumulate on the odorcontrol particles 144.

[0074] The control system of the cleaner 20 (not shown) conducts theelectrical current through the heating element 158. Electrical currentis supplied to the heating element 158 by a connector (not shown)located on the perimeter frame 150. The connector on the perimeter frame150 connects with a corresponding connector located within the frame 46of the cleaner 20.

[0075] The individual cell panels 140 are held in the Vee shapeorientation shown in FIG. 11 by conventional mechanical connectors andsupports, not specifically shown. The joints and spaces between the cellpanels 140 are sealed to confine the flow through the layers 142 and 146of the cell panels 140. Preferably the sealant between the cell panels146, and the support and connectors of the frame 46 is a suitableresilient sealing material, such as conventional biomed gel used as asealant in clean rooms. An example of such clean room biomed gel is CRG246 manufactured by Gordon Clean Room Products of Shreveport, La. Such abiomed gel forms a complete, durable and reusable non-toxic andnoncontaminating seal which conforms around the edges and surfaces ofthe cell panels 140 which it contacts. Moreover, such a biomed gelreleases from the edges and surfaces of the cell panels 140 if itbecomes necessary to replace or service those cell panels. The biomedgel thereafter re-conforms around any replacement cell panel to form acomplete, integral seal.

[0076] Each Vee shaped configuration of two cell panels 140 (three Veeshaped configurations are shown in FIG. 11) is defined in part by an endpanel 160 which is connected to the perimeter frames 150 of the two cellpanels 140 oriented in the Vee shaped configuration. Each end panel 160is connected to the pair of cell panels 140 in an airtight manner, suchas with a mechanical connector or with biomed gel. Each end panel fitswithin slots or receptacles in the frame 46 to hold its position and toconfine the flow over and through the cell panels 140.

[0077] The control system of the cleaner 20 is preferablycomputer-controlled. The control system includes a plurality of sensorslocated at selected points in the flow through the cleaner 20 formonitoring the contaminant removal, water level and liquid removalfunctions. Further sensors are connected to various active elements ofthe cleaner to control the operation of the cleaner for desiredperformance conditions. For example, the control system monitors theflow rate or speed in order to determine whether the blower 24 (FIG. 1)is functioning properly, or if the flow path has become obstructed, orthe speed of the blower needs adjusting. The control system alsomonitors the amount of water in the baffle-defining structure 50 todetermine whether the amount of water flowing through and confinedwithin the mixing zones (86, FIG. 5 and 104, FIG. 7) of the bafflestructure is at the desired level. If not, the speed or performance ofthe pump 62 (FIG. 3) is adjusted. To control the amount of watersuspended in the mixing zones, an infrared (IR) source/detector (notshown) is mounted within an air passageway 51 of the baffle structure 50to detect the amount of water therein. The control system also monitorsthe water level in the drain well 53 and delivers additional water whenneeded through the water supply pipe 70 by controlling the valve 69(FIG. 3). The control system also monitors the amount of contaminationin the diffusion plates 48, the mist eliminators 56 and the filters 57to determine when to replace or clean these elements and to signal thatthese elements need servicing. The control system also times the timeperiod for heating, and the time intervals between heating, the cellpanels 140 of the catalytic cells 65 to keep the catalyst particles 148activated. The control system controls valves to periodically drain thecontaminated water from the drain well 53 and to refresh the well 53with clean water, as well as to wash out the scrubber module 40 andcyclone 54. Many other control functions may also be performed by thecontrol system.

[0078] In addition to removing and neutralizing odors, volatile organiccompounds and toxic gas by the catalytic cell 65, some odors, volatileorganic compounds and gaseous constituents may also be removed by theaddition of chemical emulsifiers or attractants in the water or cleaningliquid of the scrubber module 40. Alternatively, the water in thescrubber module 40 may be replaced entirely with a cleaning liquid agentto chemically react with the airborne contaminants to capture and removethe contaminants and/or to convert the contaminants into a harmlesssubstance. Thus, the liquid flowing through the scrubber module may beany appropriate liquid or liquid mixture determined by the particularcontent of the contaminants.

[0079] The volumetric capacity of the cleaner 20 may be adjusted toaccommodate various different requirements for exhaust flow volumes andcontaminant concentrations. The baffle-defining structure 50 ispreferably made in modularized form, allowing multiple baffle structures50 to be organized into a larger baffle-defining collection 132 formedby placing individual baffle structures 50 side-by-side in a widthdimension, on top of one another in a height dimension, and end to endin a depth dimension to create more, longer and wider flow passageways,respectively. Increasing the number, length and width of the passageways51 by increasing the number of baffle-defining structures 50 may requirea change in the size of the housing 46 (FIG. 1). The housing and itsinternal frame are formed with rails and projections (not shown) whichallow the baffle-defining structures 50 to be conveniently inserted intothe housing and removed from it once side panels of the housing areremoved.

[0080] The cleaner 20 may include more than one liquid removal module42, or more than one cyclone 54 in each liquid removal module, arrangedin parallel in the exhaust flow path. The number of cyclones and liquidremoval modules is adjusted according to the volumetric capacity of thecleaner. Similarly, as many catalytic cells 65 and cell panels 140 maybe incorporated into the cleaner 20 as needed to accommodate thevolumetric capacity of the particular application. More than one cleaner20 may be arranged in parallel if necessary to accommodate aparticularly large exhaust flow. However, in most cases, a singlescrubber module 40, liquid removal module 42 and filtering and catalyticmodule 44 would generally prove satisfactory for most typicalapplications.

[0081] The cleaner described above provides several improvements andadvantages over previous cleaners, including high efficiency in waterscrubbing the contaminants from the exhaust flow by the enhancedair/water mixing conditions created by the scrubber module, highefficiency in removing the mist and residual particles from the air bythe centrifugal force by the liquid removal module, and effectivefiltration and conversion of odors, volatile organic compounds andhazardous gaseous constituents into benign substances which allow thesubstantial majority of the clean exhaust air to be recirculated intothe restaurant or other clean air environment. By being able torecirculate the substantial majority of the exhaust air, the thermalenergy of that exhaust air is not lost by discharge into the ambientenvironment. Instead, the thermal energy may be returned to the confinedenvironment, thereby reducing the costs and requirements to conditionmakeup air. Although a small amount of the oxygen within the air is usedin oxidizing carbon monoxide to carbon dioxide, that amount of oxygen ismade up as a result of discharging a small proportion of the cleanexhaust air into the ambient environment. The small amount of thedischarged clean exhaust air is made up by fresh air containingsufficient oxygen so as not to deplete the confined environment ofoxygen. Many other advantages and improvements will be apparent to thosehaving skill in the art, after gaining a complete understanding andcomprehension of the present invention.

[0082] Presently preferred embodiments of the invention and itsimprovements have been described with a degree of particularity. Thisdescription has been made by way of preferred example. It should beunderstood that the scope of the present invention is defined by thefollowing claims, and should not be unnecessarily limited by thedetailed description of the preferred embodiment set forth above.

The invention claimed is:
 1. A recirculation system for retainingsubstantial thermal energy content of air drawn from within a confinedenvironment as part of an exhaust flow which includes gaseouscontaminants, comprising: a collector device located within the confinedenvironment to receive and establish the exhaust flow of contaminantsand air from within the confined environment; a cleaner device connectedto receive the exhaust flow from the exhaust collector device; thecleaner device comprising a scrubber module, a liquid removal module anda filtering and conversion module connected in series through which theexhaust flow passes; the scrubber module including flow passagewaysthrough which the exhaust flow passes and into which cleaning liquid isdistributed for mixture with and entrainment of contaminants of theexhaust flow; the liquid removal module removing cleaning liquid fromthe flow from the scrubber module; the filtering and conversion modulecomprising an odor-removing filter and a catalyst; the odor-removingfilter removing odor from the flow from the liquid removal module; thecatalyst facilitating conversion of the gaseous contaminants gas in theflow from the liquid removal module into benign gaseous constituents;and a delivery device located within the confined environment to receivethe flow from the cleaner device and discharge the flow into theconfined environment.
 2. A recirculation system as defined in claim 1wherein the confined environment is a food preparation establishmenthaving an open flame cooker which produces carbon monoxide gas, odor,smoke and airborne grease as particulate and gaseous cooking exhaustcontaminants, and wherein: the collection device comprises an exhaustcollection hood located over the open flame cooker; the scrubber moduleremove substantially all of the particulate contaminants from theexhaust flow; and a catalyst facilitates conversion of the carbonmonoxide gas in the flow from the liquid removal module into carbondioxide gas.
 3. A recirculation system as defined in claim 2 wherein:the delivery device discharges the flow from the filtering andconversion module into the exhaust hood.
 4. A recirculation system asdefined in claim 1 wherein the contaminants of the exhaust flow includecarbon monoxide gas, and wherein: the catalyst operates at roomtemperature to oxidize the carbon monoxide into the carbon dioxide.
 5. Arecirculation system as defined in claim 4 wherein: the catalystutilizes air from the exhaust flow and carbon monoxide from the flow toform carbon dioxide.
 6. A recirculation system as defined in claim 4wherein: the catalyst comprises mixed manganese copper oxide.
 7. Arecirculation system as defined in claim 4 wherein: the catalystcomprises potassium permanganate.
 8. A recirculation system as definedin claim 4 wherein the contaminants from the exhaust flow include odor,and wherein: the filter comprises a carbon particle filter.
 9. Arecirculation system as defined in claim 4 further comprising: a heaterpositioned to heat the catalyst to a predetermined temperaturesufficient to regenerate catalytic characteristics of the catalyst. 10.A recirculation system as defined in claim 4 wherein the filtering andconversion module includes a catalyst cell through which the flow fromthe liquid removal module passes, the catalyst cell comprising: a layerof particles of the room-temperature catalyst; and a layer of carbonparticles.
 11. A recirculation system as defined in claim 10 wherein thecatalyst cell further comprises: a heater positioned within the layer ofcatalyst particles to heat the catalyst particles to a predeterminedtemperature sufficient to regenerate catalytic characteristics of thecatalyst.
 12. A recirculation system as defined in claim 4 wherein thefiltering and conversion module further comprises: a filter deviceconnected to receive the flow from the liquid removal device, the filterdevice comprising one of a HEPA, DOP or BAG filter.
 13. A recirculationsystem as defined in claim 1 wherein the scrubber module furthercomprises: a baffle-defining structure comprising a plurality ofvertically spaced and interdigitated deflection plates which define aserpentine-shaped flow passageway through which the exhaust flow movesgenerally upward; and a liquid distributor positioned within eachpassageway of the baffle-defining structure to flow liquid cleaningagent downward through each passageway and generally onto the deflectionplates; the baffle-defining structure further comprising a plurality ofvertically spaced deflection plates extending generally horizontally inthe passageway, each deflection plate having a main portion slopingdownward and an outer end lip portion extending from the main portion,vertically adjacent and consecutive deflection plates in the passagewayextending in opposite directions with respect to one another, thevertically spaced deflection plates interdigitating with one another,and the lip portions horizontally overlapping the main portion of atleast one vertically adjacent deflection plate to form the passageway ina serpentine manner having repeated alternating-direction turns aroundthe lip portions of the deflection plates; the liquid flows off the lipportion of each deflection plate into and through the exhaust flowturning around the lip portion to mix the exhaust flow and the liquid toentrain the contaminants in the liquid.
 14. A recirculation system asdefined in claim 13 wherein: the vertically adjacent deflection platesoverlap one another within the range of approximately 51% to 80% of thehorizontal extent of each deflection plate.
 15. A recirculation systemas defined in claim 13 wherein: the angle of each lip portion relativeto the flow around each lip portion causes at least a portion of theliquid flowing from the lip portion of the deflection plate to be drivenupward from the lip portion with the flow and mixed with the flow.
 16. Arecirculation system as defined in claim 13 wherein: the main portion ofthe immediately below-positioned deflection plate and the immediatelyabove-positioned deflection plate define a flow/liquid mixing zone inthe passageway between vertically adjacent deflection plates; the angleof each lip portion relative to the flow around each lip portion causesat least a portion of the liquid flowing from the lip portion of thedeflection plate to be driven upward from the lip portion with the flowand mixed with the flow in the mixing zone; and the lip portion of eachdeflection plate extends into the flow to create a vortex motion of theflow in the mixing zone to increase the contact of the contaminants inthe flow with the liquid.
 17. A recirculation system as defined in claim13 wherein the scrubber module further comprises further comprises: aliquid removal device connected to receive the flow from thebaffle-defining structure, the flow from the baffle-defining structurecontaining a mist of the liquid, the liquid removal device removing asubstantial majority of the liquid mist from the flow before passinginto the liquid removal module.
 18. A recirculation system as defined inclaim 17 wherein the liquid removal device comprises a cyclone.
 19. Arecirculation system as defined in claim 1 wherein the liquid removaldevice comprises: a curved sidewall structure along which the flow fromthe scrubber module moves in a curved motion to force liquid in the flowfrom the scrubber module to coalesce into liquid and drain along thesidewall structure.
 20. A recirculation system as defined in claim 19wherein contaminants in the flow are also forced against the sidewallstructure to become entrained in the liquid on the sidewall structure.21. A recirculation system as defined in claim 19 further comprising ademisting wall positioned in the flow between the scrubber module andthe liquid removal module to remove a part of the liquid mist in theflow from the scrubber module.
 22. A recirculation system for retainingsubstantial thermal energy content of air drawn from within a confinedenvironment as part of an exhaust flow which includes gaseouscontaminants, comprising: a collector device located within the confinedenvironment to receive and establish the exhaust flow of contaminantsand air from within the confined environment; a scrubber modulecomprising a passageway through which the exhaust flow from the deliverydevice moves in one direction and a liquid cleaning agent moves in anopposite direction by which to entrain contaminants from the exhaustflow within the liquid; a liquid removal module comprising a curvedsidewall structure along which the flow from the scrubber module movesin a curved motion to force liquid in the flow to coalesce on thesidewall structure and to force contaminants in the flow against thesidewall structure to become entrained in the liquid on the sidewallstructure; a filtering and conversion module comprising an odor-removingfilter and a catalyst; the odor-removing filter removing odor from theflow from the liquid removal module; the catalyst facilitatingconversion of the gaseous contaminants in the flow from the liquidremoval module into benign gaseous constituents; and a delivery devicelocated within the confined environment to receive the flow from thecleaner device and discharge the flow into the confined environment. 23.A method of recirculating air to retain substantial thermal energycontent of the air drawn from within a confined environment as part ofan exhaust flow which includes gaseous contaminants, comprising:establishing the exhaust flow of the contaminants and air from withinthe confined environment; liquid scrubbing contaminants from the exhaustflow; moving the flow after liquid scrubbing in a curved path to forceliquid mist to coalesce into liquid by centrifugal force caused bymoving the flow in the curved path; removing the coalesced liquid fromthe flow; removing odor from the flow after the coalesced liquid hasbeen removed; catalyzing gaseous contaminants into benign gaseousconstituents after the coalesced liquid has been removed; anddischarging the flow into the confined environment after the odor hasbeen removed and the gaseous contaminants have been catalyzed into thebenign gaseous constituents.
 24. A method as defined in claim 23 furthercomprising: catalyzing the gaseous contaminants into the benign gaseousconstituents at approximately room temperature.
 25. A method as definedin claim 24 further comprising: using a catalyst to catalyze the gaseouscontaminants into the benign gaseous constituents; and periodicallyheating the catalyst to a predetermined temperature greater than roomtemperature which is sufficient to regenerate catalytic characteristicsof the catalyst.
 26. A method as defined in claim 23 further comprising:collecting the air and exhaust contaminants from within the confinedenvironment in an exhaust collection hood located to establish the flowfrom within the confined environment; and discharging the flow into theconfined environment within the hood.
 27. A recirculation system asdefined in claim 23 wherein the confined environment is a foodpreparation establishment having an open flame cooker which producescarbon monoxide gas, odor, smoke and airborne grease as particulate andgaseous cooking exhaust contaminants, further comprising: collecting theexhaust flow in a collection hood located over the open flame cooker;cleaning substantially all of the particulate contaminants from theexhaust flow by liquid scrubbing; and catalyzing the carbon monoxide gasand air in the flow from the liquid removal module into carbon dioxidegas.